copy_{to,from}_user(): consolidate object size checks

... and move them into thread_info.h, next to check_object_size()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 29 insertions, 26 deletions

diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index d7d3ea637dd0..250a27614328 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -113,6 +113,33 @@ static inline void check_object_size(const void *ptr, unsigned long n,
 { }
 #endif /* CONFIG_HARDENED_USERCOPY */
 
+extern void __compiletime_error("copy source size is too small")
+__bad_copy_from(void);
+extern void __compiletime_error("copy destination size is too small")
+__bad_copy_to(void);
+
+static inline void copy_overflow(int size, unsigned long count)
+{
+        WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
+}
+
+static __always_inline bool
+check_copy_size(const void *addr, size_t bytes, bool is_source)
+{
+        int sz = __compiletime_object_size(addr);
+        if (unlikely(sz >= 0 && sz < bytes)) {
+                if (!__builtin_constant_p(bytes))
+                        copy_overflow(sz, bytes);
+                else if (is_source)
+                        __bad_copy_from();
+                else
+                        __bad_copy_to();
+                return false;
+        }
+        check_object_size(addr, bytes, is_source);
+        return true;
+}
+
 #ifndef arch_setup_new_exec
 static inline void arch_setup_new_exec(void) { }
 #endif
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index e57328896a16..80b587085e79 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -139,43 +139,19 @@ extern unsigned long
 _copy_to_user(void __user *, const void *, unsigned long);
 #endif
 
-extern void __compiletime_error("usercopy buffer size is too small")
-__bad_copy_user(void);
-
-static inline void copy_user_overflow(int size, unsigned long count)
-{
-        WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
-}
-
 static __always_inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-        int sz = __compiletime_object_size(to);
-
-        if (likely(sz < 0 || sz >= n)) {
-                check_object_size(to, n, false);
+        if (likely(check_copy_size(to, n, false)))
                 n = _copy_from_user(to, from, n);
-        } else if (!__builtin_constant_p(n))
-                copy_user_overflow(sz, n);
-        else
-                __bad_copy_user();
-
         return n;
 }
 
 static __always_inline unsigned long __must_check
 copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-        int sz = __compiletime_object_size(from);
-
-        if (likely(sz < 0 || sz >= n)) {
-                check_object_size(from, n, true);
+        if (likely(check_copy_size(from, n, true)))
                 n = _copy_to_user(to, from, n);
-        } else if (!__builtin_constant_p(n))
-                copy_user_overflow(sz, n);
-        else
-                __bad_copy_user();
-
         return n;
 }
 #ifdef CONFIG_COMPAT